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Need help editing lagrange point tiles
http://forums.nesdev.com/viewtopic.php?f=21&t=9749
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Author:  Drakon [ Sun Jan 27, 2013 11:53 am ]
Post subject:  Need help editing lagrange point tiles

I learned how to make a table and find japanese text in lagrange point. I can now change the japanese text into different japanese text, but I want to change it into english which requires editing the text graphic tiles. Every graphic tile editing program I use doesn't display the lagrange point hiragana tiles in a nice orderly pattern, other roms like megaman 2 works fine with the same editors. Is there something special I need to do to get lagrange point to work for editing the text graphic tiles?

Author:  rainwarrior [ Sun Jan 27, 2013 6:15 pm ]
Post subject:  Re: Need help editing lagrange point tiles

Since Lagrange Point is CHR-RAM, all the tiles are stored in the PRG-ROM portion, but looking at it with YY-CHR, I don't see much in there that looks like raw tile data, which I think means that the tiles in Lagrange Point are compressed.

You're probably going to need to disassemble or at least debug/trace the code that uncompresses tile data from PRG-ROM into CHR-RAM, so that you can reverse engineer the compression method used. If you're lucky it'll be some sort of simple RLE scheme, but I have no guess as to what it uses, offhand. Just put a breakpoint on writes to CHR-RAM and start tracing it out.

Author:  Drakon [ Sun Jan 27, 2013 6:51 pm ]
Post subject:  Re: Need help editing lagrange point tiles

Yeah the only way to really make out the font tiles is by setting the software to 1bpp. Gideon Zhi was kind enough to explain on the rom hacking forum that the tiles in the game are compressed. He says the text is also compressed....which is odd....I built a table to find text and managed to change a word from one japanese word into another japanese word just fine. Anyway apparently there's no software out there that supports the tile compression of the game, I'm really terrible at figuring out how to uncompress something (I don't know assembler language at all haha). I don't think I'd be able to figure this one out on my own. I would have no clue how to set a breakpoint for chr ram writes.

God I wish they had made 1 megabyte famicom games.

Author:  tepples [ Sun Jan 27, 2013 8:07 pm ]
Post subject:  Re: Need help editing lagrange point tiles

Drakon wrote:
God I wish they had made 1 megabyte famicom games.

Metal Slader Glory?

Author:  Drakon [ Mon Jan 28, 2013 6:43 am ]
Post subject:  Re: Need help editing lagrange point tiles

tepples wrote:
Drakon wrote:
God I wish they had made 1 megabyte famicom games.

Metal Slader Glory?

Really? Well they said on the romhacking forum that for whatever reason the lagrange point rom can't be expanded to one megabyte.

Author:  thefox [ Mon Jan 28, 2013 7:05 am ]
Post subject:  Re: Need help editing lagrange point tiles

Drakon wrote:
tepples wrote:
Drakon wrote:
God I wish they had made 1 megabyte famicom games.

Metal Slader Glory?

Really? Well they said on the romhacking forum that for whatever reason the lagrange point rom can't be expanded to one megabyte.

That's a limitation of VRC7 mapper.

Author:  Dwedit [ Mon Jan 28, 2013 6:27 pm ]
Post subject:  Re: Need help editing lagrange point tiles

Throw in a latch somewhere and call it a new mapper.

Author:  lidnariq [ Mon Jan 28, 2013 8:57 pm ]
Post subject:  Re: Need help editing lagrange point tiles

Dwedit wrote:
Throw in a latch somewhere and call it a new mapper.
That's kind of a pain; there isn't really a single-IC solution for that. Any solution would need to sit somewhere the VRC7 ignores, which basically means below RAM or one of the (now) unused bits in the mirroring or PRG or CHR bank controls. The hardware instantiation of that will be a pain: it's at least a '139 and a '161, and I'd be tempted to add a '153, and at that point using a CPLD that just implements the full eight bits available to the bank select will probably hurt less.

Author:  rainwarrior [ Mon Jan 28, 2013 10:36 pm ]
Post subject:  Re: Need help editing lagrange point tiles

Drakon wrote:
I don't know assembler language at all haha


Well, there's never a better time to learn than now. ;)

Author:  Dwedit [ Tue Jan 29, 2013 3:34 am ]
Post subject:  Re: Need help editing lagrange point tiles

What about repurposing one of the high CHR selection lines as a 512K PRG selector?

Author:  Drakon [ Tue Jan 29, 2013 7:17 am ]
Post subject:  Re: Need help editing lagrange point tiles

rainwarrior wrote:
Drakon wrote:
I don't know assembler language at all haha


Well, there's never a better time to learn than now. ;)

Can't be bothered right now. Don't have enough interest to figure it out I suppose.

Still if someone here could come up with a hardware solution to get the vrc7 to support 1 megabyte roms I'm sure that would make the fanslation happen much quicker. Unless the game would require reprogramming to support the added size.

Author:  lidnariq [ Tue Jan 29, 2013 12:48 pm ]
Post subject:  Re: Need help editing lagrange point tiles

Dwedit wrote:
What about repurposing one of the high CHR selection lines as a 512K PRG selector?
We'd need to write the same value to all 8 CHR banking registers, much like using the MMC1 on SNROM in 4k mode. If the game has an obvious place to be split once, and it's easy enough to figure how LP deals with storing CHR banks to prevent it from writing the wrong value and mid-render PRG bankswitching... but that sounds like a pain.

One could also rewire a VRC1or Irem H3001 in lieu of the CPLD I suggested in my previous post.

Ultimately, unfortunately, the PowerPak only has 512KB of RAM-for-PRGROM anyway, so a 1MB translation would be effectively restricted to emulators and reproductions anyway.

One final possibility that addresses that is doing something like the TQROM CHR RAM+ROM, and wire up a 128 or 256 KB CHR-ROM above the 8KB of CHR-RAM that LP uses. But this will require moving massive numbers of tiles out of compressed format in PRG into CHRROM.

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